U.S. patent number 6,472,068 [Application Number 09/697,231] was granted by the patent office on 2002-10-29 for glass rupture disk.
This patent grant is currently assigned to Sandia Corporation. Invention is credited to Edwin K. Beauchamp, S. Jill Glass, Scott D. Nicolaysen.
United States Patent |
6,472,068 |
Glass , et al. |
October 29, 2002 |
Glass rupture disk
Abstract
A frangible rupture disk and mounting apparatus for use in
blocking fluid flow, generally in a fluid conducting conduit such
as a well casing, a well tubing string or other conduits within
subterranean boreholes. The disk can also be utilized in
above-surface pipes or tanks where temporary and controllable fluid
blockage is required. The frangible rupture disk is made from a
pre-stressed glass with controllable rupture properties wherein the
strength distribution has a standard deviation less than
approximately 5% from the mean strength. The frangible rupture disk
has controllable operating pressures and rupture pressures.
Inventors: |
Glass; S. Jill (Albuquerque,
NM), Nicolaysen; Scott D. (Albuquerque, NM), Beauchamp;
Edwin K. (Albuquerque, NM) |
Assignee: |
Sandia Corporation
(Albuquerque, NM)
|
Family
ID: |
24800342 |
Appl.
No.: |
09/697,231 |
Filed: |
October 26, 2000 |
Current U.S.
Class: |
428/410;
501/70 |
Current CPC
Class: |
B32B
17/06 (20130101); E21B 21/103 (20130101); E21B
33/12 (20130101); Y10T 428/315 (20150115) |
Current International
Class: |
B32B
17/06 (20060101); E21B 33/12 (20060101); E21B
21/10 (20060101); E21B 21/00 (20060101); B32B
017/00 () |
Field of
Search: |
;501/70 ;166/317 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Bradshaw, W., "Sress profile determination in chemically
strengthened glass using scattered light," J. of Material Sci.,
1979, 14, 2981-2988. No month. .
Shetty, D.K, Rosenfield, A.R., McGuire, P., Bansal, G.K., and
Duckworth, W.H., "Biaxial flexure tests for ceramics," J. Ceram.
Soc., 1980, 59(12), 1193-1197, No month. .
American Society for Testing & Materials (ASTM), "Standard test
method for biaxial flexure strength (modulus of rupture) of ceramic
substrates," ASTM F394-78, 1991, 313-316, No month..
|
Primary Examiner: Jones; Deborah
Assistant Examiner: Blackwell-Rudasill; Gwendolyn
Attorney, Agent or Firm: Klavetter; Elmer A.
Government Interests
This invention was made with Government support under Contract No.
DE-AC04-94AL85000 awarded by the Department of Energy. The
Government has certain rights in the invention.
Claims
We claim:
1. A frangible glass rupture disk for blocking fluid flow wherein
the frangible glass rupture disk comprises a pre-stressed glass
with a strength distribution having a standard deviation less than
approximately 5% from the mean strength.
2. The frangible glass rupture disk of claim 1 wherein the
pre-stressed glass is pre-stressed using a double ion-exchange
process that produces a compressive stress profile with the maximum
in the compressive stress occurring below the surface of the
glass.
3. The frangible glass rupture disk of claim 1 wherein the
pre-stressed glass has a composition in the range of approximately
(by weight percent) 62-73% SiO.sub.2, 12-15% Na.sub.2 O, 0.3-10%
CaO, 0-3% MgO, 0-4% K.sub.2 O, 0-17% Al.sub.2 O.sub.3, 0-0.7%
TiO.sub.2, 0-0.2% Fe.sub.2 O.sub.3, and 0-0.04% SnO.sub.2.
4. The frangible glass rupture disk of claim 3 wherein the
pre-stressed glass has a composition of approximately (by weight
percent) 62% SiO.sub.2, 13% Na.sub.2 O, 0.3% CaO, 3% MgO, 4%
K.sub.2 O, 16% Al.sub.2 O.sub.3, 0.7% TiO.sub.2, 0.2% Fe.sub.2
O.sub.3, and 0.04% SnO.sub.2.
5. The frangible glass rupture disk of claim 4 wherein the
pre-stressed glass has a mean strength of approximately 540 MPa and
a Weibull modulus of approximately 60.
6. The frangible glass rupture disk of claim 5 wherein the glass
rupture disk has a probability of failure of less than 0.05 at
operating pressures of less than approximately 1700 psi and has a
probability of failure of greater than 0.95 at pressures greater
than approximately 2100 psi.
7. The frangible glass rupture disk of claim 3 wherein the
pre-stressed glass has a composition of approximately (by weight
percent), 73% SiO.sub.2, 15% Na.sub.2 O, 10% CaO, and 2% trace
elements.
8. The frangible glass rupture disk of claim 7 wherein the
pre-stressed glass has a mean strength of approximately 270 MPa and
a Weibull modulus of approximately 45.
9. The frangible glass rupture disk of claim 1 wherein the
frangible glass rupture disk is used for blocking fluid flow in a
fluid-conducting conduit, said fluid-conducting conduit selected
from a well casing, a well tubing string, and a subterranean
borehole.
10. The frangible glass rupture disk of claim 1 wherein the
frangible glass rupture disk is an approximately circular disk.
11. The frangible glass rupture disk of claim 10 wherein the
circular disk has a thickness of between approximately 0.07 inches
to 0.125 inches.
12. The frangible glass rupture disk of claim 10 wherein the
circular disk has a diameter of between approximately 0.5 inches to
1.5 inches.
13. The frangible glass rupture disk of claim 1 wherein, after
rupture has occurred at the failure pressure, greater than 95% (by
mass) of glass fragments formed have a maximum dimension less than
approximately 3 millimeters.
Description
BACKGROUND OF THE INVENTION
The invention relates to a glass rupture disk and, more
particularly, to a glass rupture disk and mounting apparatus with
controllable rupture characteristics positioned to selectively
restrict fluid flow in a well.
In the general process for drilling and production of oil and gas
wells, at that point in the process where a hydrocarbon formation
has been located at a particular depth, normally an exterior casing
would be lowered down the bore hole through the area of production,
known as the production zone. The exterior casing is perforated
with the use of a perforating gun or the like. Using electric wire
line and setting tools, or some other means, a permanent type
packer, referred to as a "sump packer" is usually set below the
perforations. Subsequently, an internal tubing string, together
with sand screen and blank pipe, packer and packer extension,
hydraulic setting tool, cross-over tool, and wash pipe, are
positioned within the exterior casing to engage with the "sump
packer". The annulus between the sand screen and the exterior
perforated casing is packed off, utilizing certain procedures. This
packing off is necessary so that the interior tubing would be
utilized to carry the recovered hydrocarbons to the surface. The
area around the perforations is prepared, so that the flow of
hydrocarbons can commence.
After gravel packing is complete, oftentimes the well can not
necessarily be pressure balanced. The formation, under these
conditions, can tend to absorb the well fluid into the production
zone or the fluid in the zone can tend to flow into the well. In
either case, this could lead to unacceptable (a) loss of expensive
well fluid, (b) damage to the formation, (c) danger of a potential
well blow-out or co-mingling of formation fluids. There is a need
in the art for a device, such as a valve or rupture disk, that can
prevent the movement of fluids within the well and under varying
degrees of pressure differential within the well.
In conventional practice, when a well conduit is desired to be
temporarily closed off, it is common to set a plug within the
conduit to preclude the flow of fluids at the preferred location.
Alternatively, a temporary plug can be installed in the lower end
of the production tubing to permit tests for the pressure bearing
integrity of the tubing. Additionally, the plug can permit the
selective pressurization of the tubing to permit the operation of
pressure sensitive tools within the tubing. Regarding oil and gas
wells, there are many types of plugs that are used for different
applications. As an example, there are known removable plugs
typically used during cementing procedures that are made of soft
metals that may be drilled out of the conduit after use. Plugs that
can be removed from a well intact are referred to as "retrievable"
plugs. Removal, however, requires mechanical intervention from the
surface of the well. Common intervention techniques include
re-entry into the well with wireline, coiled tubing, or tubing
string. Because other well operations cannot be performed during
such work, the retrieval of the temporary plug delays the well
operations and adds additional cost to the well operations.
After a conventional type plug has been set and it subsequently
becomes necessary to reestablish flow, any tools that have been
associated with the plug during its use must be removed or "pulled"
from the well to provide access to the plug for the removal
process. The pulling of tools and removal of the plug to
reestablish flow within a downhole conduit often entails
significant cost and rig downtime. It is, therefore, desirable to
develop a plug that can be readily removed or destroyed without
either significant expense or rig downtime.
Known conduit plugs incorporating frangible elements that must be
broken from their plugging positions include frangible disks that
are stationarily located within tubular housings and flapper type
elements. One technique uses a phenolic disk packed with
explosives. Breakage can be initiated by piercing the plug to cause
destructive stresses within the plug's body, mechanically impacting
and shattering the plug, or increasing the pressure differential
across the plug until the plug is "blown" from its seat. After
breakage has occurred, the resulting shards or pieces must be
washed out of the well bore with completion fluid or the like in
many situations. Because most known designs call for a relatively
flat plug to be supported about its periphery, the plug commonly
breaks from the interior outwardly and into relatively large pieces
that can interfere with other well completion activities.
Another temporary plug technique uses a glass disk to temporarily
seal the well tubing. When ruptured with fluid pressure,
explosives, or mechanical devices, the glass fractures into
relatively small fragments to open the tubing bore. Although the
glass fragments are generally smaller than the fragments left by a
phenolic disk, the glass disks are brittle and do not reliably
support large differential fluid pressures within the well. The
glass surfaces are also easily damaged leading to significant
strength degradation of the glass. As a result, the glass disks can
inadvertently rupture, leading to failure of the completion
operations.
DESCRIPTION OF DRAWINGS
FIG. 1 shows the strength distribution and probability of failure
for two different glass formulations with high Weibull moduli
(m).
FIG. 2 shows the effect of Weibull modulus of glasses with similar
strengths on failure probability.
FIG. 3 shows an illustration of the apparatus of the present
invention.
FIG. 4 shows the relationship between applied stress and
operating/failure pressure for one embodiment.
FIG. 5 shows an example of a stress profile for the glass rupture
disk.
DESCRIPTION OF SPECIFIC EMBODIMENTS
According to the present invention, a frangible rupture disk is
provided for use in blocking fluid flow, generally in a fluid
conducting conduit such as a well casing, a well tubing string or
other conduits within subterranean boreholes. The disk can also be
utilized in above-surface pipes or tanks where temporary and
controllable fluid blockage is required. The frangible rupture disk
is made from a pre-stressed glass with controllable rupture
properties wherein the strength distribution, as measured by
biaxial flexure tests using ring-on-ring loading (D. K. Shetty, A.
R. Rosenfield, P. McGuire, G. K. Bansal, and W. H. Duckworth, J.
Am. Ceram. Soc., 1980, 59,12, 1193-97; incorporated herein by
reference), has a standard deviation less than approximately 5%
from the mean strength. Standard pre-stressed and annealed glasses
have strength distributions with large standard deviations
(generally about 20%); if these glasses were used in rupture disks,
it would generally result in rupture disks that can fail at fluid
pressures lower than the desired failure pressure and can survive
at pressures above the desired failure pressure. In a typical
application using the rupture disk of the present invention, a
frangible rupture disk is provided wherein the well casing or pipe
can operate reliably at a specified operating pressure (for
example, about 2000 psi), preventing fluid flow between the
external environment and the internal pipe or well casing
environment. The rupture disk can be designed to reliably rupture
at a pressure at least 5% higher than the operating pressure (for
example, approximately 2500 psi). Multiple rupture disks can be
utilized in such a pipe or well casing.
The glass used in the glass rupture disk of the present invention
is a glass that is pre-stressed using a double ion-exchange process
that produces a stress profile with the maximum in the compressive
stress below the surface of the glass, rather than at the surface.
As a result, the strength distribution is narrow, producing a
standard deviation for the glass strength less than approximately
5% of the mean strength. As characterized by the Weibull modulus
for the strength distribution, the glass has shown Weibull moduli
in the range of 60, compared with standard glasses and ceramics
with Weibull moduli in the range of 5-15. (The Weibull modulus
defines the strength data scatter of a given volume of ceramic
under a uniform stress.) The narrow strength distribution is
important in allowing the disk of the present invention to function
reliably. Glasses with low Weibull moduli are unreliable in
controllably blocking fluid flow as they can unexpectedly fragment
at the operating pressures rather than the designed rupture
pressure, or survive at pressures well above the specified failure
pressure. For the glass rupture disks of the present invention, a
Weibull modulus of greater than approximately 25 is required.
One of the glasses used in the glass rupture disk of the present
invention is a sodium aluminosilicate glass where sodium ions are
replaced by potassium ions using normal ion exchange procedures.
Some of the potassium ions are exchanged back to sodium near the
surface to produce a compressive stress profile below the surface
that results in a crack arrest phenomenon. Glass compositions,
comprised of approximately (by weight percent) 62-73% SiO.sub.2,
12-15% Na.sub.2 O, 0.3-10% CaO, 0-3% MgO, 0-4% K.sub.2 O, 0-17%
Al.sub.2 O.sub.3, 0-0.7% TiO.sub.2, 0-0.2% Fe.sub.2 O.sub.3, and
0-0.04% SnO.sub.2 were used to develop the glass rupture disks of
the present invention. The glass composition chosen was first
annealed in air, for example at 560.degree. C. for several hours,
and then subjected to the first ion exchange with potassium (for
example, using KNO.sub.3) at elevated temperature (for example, at
500.degree. C.) and then subjected to the second ion exchange in a
potassium/sodium mixture (for example, KNO.sub.3 /NaNO.sub.3),
again at an elevated temperature (for example, at 400.degree. C.).
One glass composition, comprised of approximately (by weight
percent) 62% SiO.sub.2, 13% Na.sub.2 O, 0.3% CaO, 3% MgO, 4%
K.sub.2 O, 16% Al.sub.2 O.sub.3, 0.7% TiO.sub.2, 0.2% Fe.sub.2
O.sub.3, and 0.04% SnO.sub.2, when treated by the above-described
double-exchange process, produced a characteristic (mean) strength
of 540 MPa with a strength distribution as shown in FIG. 1, where
this composition has a Weibull modulus of approximately 60. FIG. 2
shows the strength distribution for this glass and two other
glasses with the same characteristic strength, but with lower
Weibull modulus values of 5 and 10. This figure demonstrates how
the glass of the present invention (Weibull modulus=60) can be used
to operate reliably (less than 0.05 probability of failure) at a
pressure less than approximately 500 MPa and be used to rupture
reliably (greater than 0.95 probability of failure) at a pressure
of greater than approximately 580 MPa.
One commercial soda lime silicate glass composition effectively
used to produce the narrow strength distribution required by the
method of the present invention was (in approximate weight
percent), 73% SiO.sub.2, 15% Na.sub.2 O, 10% CaO, and 2% trace
elements. This particular composition produced a characteristic
strength of 275 MPa with a strength distribution as shown in FIG.
1, where this composition has a Weibull modulus of approximately
40.
The glass rupture disk of the present invention can be of various
sizes, geometries and thicknesses. Typical is a circular disk with
a thickness ranging from approximately 0.070 inches to 0.125 inches
and a diameter ranging from approximately 0.5 to 1.5 inches.
For use in a fluid flow conduit, such as a pipe or well casing, the
rupture disk must be situated in the wall of the conduit and
therefore must be mounted and sealed in the conduit as part of a
apparatus that can inserted into the conduit wall. The conduit will
have an opening, generally circular, with cross-sectional dimension
small than the dimension of the glass rupture disk. The glass
rupture disk will be part of an apparatus that is mounted into the
opening, providing stability to the glass rupture disk to be
situated such that the rupture disk provides a barrier between the
internal environment of the conduit and the external environment.
The apparatus also provides a seal such that the strength of the
seal is greater than the rupture pressure of the glass rupture
disk. Because the conduit can be bent during use, the apparatus
holding the glass rupture disk must be capable of withstanding the
stresses that occur during conduit bending and must not put
excessive stresses on the glass rupture disk that would cause it to
rupture.
In one embodiment, the conduit is a cylinder where the apparatus
holding the glass rupture disk is a threaded nut with a cavity to
hold the glass rupture disk, with a gasket that serves to both seal
the disk in the conduit but also isolates the disk from bending
loads on the conduit, such as can occur when a pipe is inserted
into a well bore. FIG. 3 shows an illustration of the apparatus
where the glass rupture disk diameter is from 0.5-1.0 inches, the
disk thickness is approximately 0.125 inches, and the conduit wall
thickness is between approximately 0.25-0.5 inches. The apparatus
is a threaded nut 12 with a cylindrical cross-section that can be
threaded into a pre-threaded conduit wall 11, where the glass
rupture disk 13 is positioned between the threaded nut and some
portion of the conduit wall, thereby blocking fluid flow between
the interior of the conduit and the exterior environment, with a
gasket 14 positioned between the glass rupture disk and conduit
wall to aid in sealing. The threaded nut 12 must seal the glass
rupture disk 13 to the conduit wall sufficient to block fluid flow
such that the apparatus can not be dislodged by pressure within the
interior of the conduit at pressures less than the glass rupture
pressure. This sealing can be accomplished by a clamping means on
the exterior of the conduit, by adhesive means between the
apparatus and the conduit or by threaded screws that connect the
apparatus to the conduit that can be tightened to a determined
torque to achieve an adequate seal for the desired operating and
glass rupture pressure. FIG. 3 shows an apparatus with multiple
holes 15 around the periphery where these threaded screws can
connect the apparatus to the conduit.
EXAMPLE
A sodium aluminosilicate glass was obtained with the approximate
composition (in approximate weight percent), 62.3 SiO.sub.2, 12.8
Na.sub.2 O, 0.3 CaO, 3.3 MgO, 3.5 K.sub.2 O, 16.4 Al.sub.2 O.sub.3,
0.7 TiO.sub.2, 0.2 Fe.sub.2 O.sub.3, and 0.04 SnO.sub.2. Circular
glass rupture disks with diameters of approximately 0.5-1.0 inches
were prepared. The thicknesses were approximately 0.07 inches. This
particular composition produced a characteristic strength of 539
MPa and strength distribution as shown in FIG. 1. FIG. 4 shows the
relationship between the strength distribution of the glass as
measured by the standard ring-on-ring loading method and the
corresponding characteristic pressure when the glass is utilized in
the apparatus of the present invention at the specified diameter
and thickness. Variation of the thickness and diameter of the disks
result in different characteristic strengths, so that the disk
failure pressure and operating pressure can be controlled by
varying these geometric characteristics. This glass was first
annealed in air, for example at 560.degree. C. for several hours,
and then subjected to the first ion exchange with potassium (using
KNO.sub.3) at 500.degree. C. and then subjected to the second ion
exchange in a potassium/sodium mixture (KNO.sub.3 /NaNO.sub.3), at
400.degree. C. These treatments produced glass rupture disks with a
glass rupture pressure of approximately 2100 psi and were designed
to operate up to pressures of approximately 1700 psi.
Stress profiles were measured in ion-exchanged glass disks by
measuring the birefringence associated with the central tension
(Bradshaw, W., J. of Material Sci., 1979, 14, 2981-2988;
incorporated herein by reference). The stress profile was measured
using the changes in the tensile stress at the midplane of a disk
as layers of the disk were removed by etching in hydrofluoric acid.
The tensile stress was determined by measuring the stress
birefringence (optical retardation). FIG. 5 shows an example of a
stress profile for the glass rupture disk using the stated glass
composition formulation, showing that the maximum compressive
stress occurs below the surface of the glass rupture disk.
Mechanical strength distributions were measured using biaxial
flexure tests on cylindrical disks with ring-on-ring loading.
Samples were tested with nominal thicknesses ranging from
approximately 0.07 inches to 0.125 inches. The Weibull plots (FIG.
1) demonstrate that the method of pre-stressing the glass
compositions tested using the double ion-exchange method produces
glasses with narrow strength distributions. FIG. 1 shows typical
strength distributions for two of the glasses used in the present
invention. For a varying group of glasses that can be used in the
glass rupture disk of the present invention, the Weibull moduli
ranged from 25 to greater than 60 for varying stress rates and disk
thicknesses.
When the disks ruptured, the mass of the fragments ranged from less
than 0.1 g to approximately 1.2 g, with greater than 95% of the
fragments (by mass) having sizes less than approximately 3.0
mm.
The glass rupture disks were placed in an apparatus as illustrated
in FIG. 3 and designed for a maximum conduit bend of 12.degree.
C./100 ft where the conduit has a maximum diameter of 5.5 inches
and a wall thickness between approximately 0.25-0.5 inches. The
threaded nut can be made of any material compatible with the fluid
conduit; stainless steel can be commonly used. The gasket material
must be sufficiently elastic to provide an adequate seal. A
suitable material for use in oil/gas application that was used in
the apparatus of the present invention was Viton.RTM. (an elastomer
that is a copolymer of vinylidene fluoride and
hexafluoropropylene).
The apparatus was screwed into the wall of the conduit and screws
inserted in eight holes along the periphery of the nut and
tightened to a torque of approximately 28 ft-lbf (38 joules), which
was based on analyses that showed that this torque would produce a
seal sufficient to withstand a pressure of greater than 2100 psi.
The apparatus thus described withstands an operating pressure of
1700 psi and ruptures at approximately 2100 psi.
The invention being thus described, it will be obvious that the
same may be varied in many ways. Such variations are not to be
regarded as a departure from the spirit and scope of the invention,
and all such modifications as would be obvious to one skilled in
the art are intended to be included within the scope of the
following claims.
* * * * *